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KS relocation mod question

5K views 34 replies 9 participants last post by  ShiftingSkys 
#1 ·
I'm getiing ready to do the knock sensor relocation mod on my 2002 SC xterrra because it is apparently stuck in safe mode due to a faulty knock sensor. I have the parts and the instructions (thanks guys!) but the x in the photos is different from mine and i'm not sure where on the intake manifold to mount my new ks. any ideas? here's a pic of mine, and a link to the instructions i'm using with pics at bottom
http://tunfs.yuku.com/topic/363/Knock-Sensor-Relocate-2002-Fronty-ODB2-code-P0328-or-PO327?page=1
 

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#2 ·
If you going in to replace the KS just replace it. I don't suggest the relocation for your S/C motor. The KS is there to protect your motor. With it relocated it cannot do its job and detect a knock. You can possibly reduce the life or ruin your motor. I'd rather have safe mode than NO mode!
 
#3 ·
you know what it feels like when u try to start in 2nd gear rather than first? that's what my truck feels like all the time. it has no power at all. I am not confident enough to start removing the entire intake manifold, supercharger, and whatever else is all in the way to get at the knock sensor. I've been repeatedly refered to this mod as the best option for me. It's not irreversible so if it doesnt work I can put it back the way it is now and rob a liquer store to pay for the repairs. :(
I still don't know where to locate the new sensor tho, so maybe i'll just try the by-pass thing. I didn't really want to do that but, I can't drive the truck the way it is now...
 
#4 ·
Everyones got an opinion here, some based on truths and some based on myths.

If anything the way rotational mass works a farther out working knock sensor will be more sensitive then a closer in one. At any rate there should be a few open holes on the passenger side of the intake manifold that you can put a bolt in to relocate the sensor.
 
#5 ·
what kind of gas do you use? I think you have another issue if the truck is "not driveable this way" I would look into that first.
If you decide to do the relocation for your sc model be prepared for the catalyst's melting internally and a significantly reduced motor life. At work I've seen many people do the relocation and it never was a smart choice in the end. I think the engineers at Nissan thought long and hard of where to put that sensor.
Just my two cents
 
#6 ·
truck still gutless after ks bypass

I ended up doing the $2 by-pass fix, with questionable results. I have noticed some improvement in power, but not nearly back the way it should be. I have been using only hi octane fuel, plus octane boost in every second tank, for the past month since the problem started. If I hadn't seen the thing on "Marketplace" that said there is no difference between regular and premium gas to most vehicles I probably would never have used regular gas in the first place, which seems to be the cause of all this.
On Monday I will take it back to the shop and have them scan for codes again and see what comes up, as well as give me an estimate to fix the muffler, which is rattling and ticking. I suspect this is the cause of the P0430 (Catalyst low efficiency) code. In the meantime I will try not to drive it anymore than necessary as i don't want to cause anymore damage.
I am SO DISAPPOINTED with this truck. I've wanted an xterra ever since I first saw them, and am now in the hole for nearly $10,000 and dont have a properly functioning vehicle. I have only had the thing since Oct, I bought it from a used car dealer on the mainland, it has no warranty, and I can't take it back. Its an 02 with 140,000km on it now, it should have been good for a few years with nothing but regular maintenence. this is crap. Im at the point where i'd just get rid of it, at a loss, if i thought i could...
 
#7 ·
i know i how you feel. if you were local i would help you replace your ks. i replaced mine and love it but it was a entire day doing it but i would have no problems replacing it again since itll be easier the next time i have to do it.
 
#8 ·
Have you had your car properly diagnosed. You are knocking and something is causing it, check your timing, make sure you are using the right fuel and check your plugs and wires. maybe might want to clean out your throttle body. keep it simple dont over complicate it

Edited to add

Check out your catalytic converter it may have given up the ghost
 
#9 ·
you guys are right, there must be more problems than just the obvious. Monday i'm going to try to get a full diagnostic and take it from there. I'm having a really hard time finding anyone who knows anything about this, let alone is willing to work on it. I don't want to take it to the dealership, they're too far away and they've treated me like crap from day 1 anyway.
I want to thank you guys tho, this forum, the DIYs, and everyone who's shared their knowledge and opinions. You have been a huge help! All this computerized stuff is totally new to me (shoulda stuck with pre 1990 Ford!) and I'd have been totally lost without you, so thanks everyone.
I'll be back with more questions after I get more info...
 
#10 ·
Ok, Ill see if I can help you a little. Since you are a local and all!
tell me more about your issue...
Is it running rough or does it have a lack of power?
you say you have a catalyst code? that can definitely cause a lack of power if the previous owner used regular owner and the cats are melted/plugged.
check timing as previously stated
timing belt been done? maybe jumped a tooth?
Mass air flow sensor readings ok?
also get them to check the waste gate on supercharger Ive seen them stick open and cause no boost situations
more info please....
 
#11 ·
So far it's like this: The problems started about a month ago (3months to the day I bought it). The first thing was the engine losing power. It would feel like the clutch was slipping (way after it had engaged) and the revs would go really high just as it hit 3500rpm, when the supercharger should kick in (I could always feel the extra power when it ran properly) and the revs would come back down and run normally. Then I noticed the rattle in the muffler, figured i'd maybe knocked something loose while off road (I've only had it off road twice, and not since the problems started). The problem with the engine got worse and worse until I have almost no power at all. Feels like when u try to start in 2nd gear instead of first, but ALL the time. I took it in for a code scan last week and got the ks code P0328, and the low catalyst efficiency code P04030. Yesterday I tried the ks by-pass mod, and initally thought I had more power but now guess it must have been wishful thinking. It's worse than ever now, and as of today running rougher too.
Tomorrow I will try to find somewhere to run a full diagnostic and see what that shows.
I bought it from a used car place in Burnaby, Luxor motors, and there's no warranty or anything, besides I'm on the Island so just getting it over there is a big hassle. I've been in touch with the dealership in Nanaimo a few times but they treated me like crap, I don't expect much different from the one in Victoria but I'll try them tomorrow.
I'm not going to drive it anymore except to take it for diagnostic. I guess I should probably undo the bypass, good thing I thought of that when I did it. Once I have a better idea of what's going on I'll try to figure out what to do...
 
#13 ·
yay! Good news: I found someone local who used to work for nissan and owns 01 frontier w sc, same engine as mine! Truck goes in wed am for diagnostic. Talked to him on the phone, he said all the same things u guys have said, and is confident he can find and fix the problem(s). Bad news: it ain't gonna be cheap, shop time is just under $100/ hr. Good &bad news: parents going t pay for repairs, add to the many thousands I still owe them.
Ah well, overall i suppose things could be worse, at least I should be back on the road soon, that'll make me super happy. The body lift, new tires, bush bumper, etc will just have to wait that much longer, i'm glad the x's are sweet just stock :)
 
#14 ·
it's the clutch?!

ok, took x into shop this am, they just called back to say the problem is the clutch. I am surprised, I really didn't think that's what it was, I've had clutches go on other vehicles and it wasn't anything like this...
He says I have no power because the clutch is not engaging fully until revs are higher.
now waiting for call back with estimate.
 
#17 ·
I am sorry that it has not been easy sailing for you. On a side not though
Wow. This must be a funny but bumpy road for you. To suspect the Supercharger the whole time and then get T-Boned by a clutch diagnosis damn. (let me know if im being rude)

I do have a question though. If it is the clutch did he give an explanation for the codes that you pulled?

In a way having the clutch go though is a good thing. Looks like it was not the X failing but just a maintenance item.
Having troubles with the supercharger would really suck and I would have probably felt the same way you did. I have a friend who owns a 1996 TT Supra and is having turbo issues. They do not always spool up. he lost a 0-60 to a Lexus. He was not happy.
 
#18 ·
Ya crazy right!? No of course ur not being rude, I'm on here because I am always interested in what u guys think.
I just have the shit luck sometimes. But actually I was expecting probs with the cats, sensors, etc, and double the repair cost. Clutches need to be replaced eventually anyway, and to get my X back running, and completely checked out with a clean bill of health, I guess I'll be pretty happy :)
(then I can focus on the windows, wipers, washer fluid resiviour, and cd player that don't work)
The guys at the shop say I have a good truck and nothing else is wrong with it. I asked about the codes and he said the KS code is common on all Nissans and not to worry about it, just stick with the hi-test gas, and the catalyst code is just an o2 sensor which is an easy fix. I hope they are right in this...
A day or two and I'll be back on the rd and in the mud, fingers xed :)
 
#19 ·
Well having a knock sensor code is not always a bad thing. A lot of people and even some mechanics assume that when they get that error code, it means the knock sensor is bad. Even worse, some mechanics will tell you that the knock sensor is bad when you get that code and have you fork over $1000 for them to "fix" it when that isn't the problem. A knock sensor code means just that... something has tripped the knock sensor. Also, a knock sensor code will not set off your check engine light. It is a hidden error code. Probably 60% of the xterras on the road right now are riding around with that code and will never know it until something else throws the CEL. :D
 
#20 ·
Drake speaks the truth. Could be the o2, after looking at the wiring diagram, they are four wire sensors. They are powered heater o2 sensors and they could be not heat up fast enough and is giving the PCM a bad signal throwing off your fuel trim. Ad causing you to go rich tripping the knock code?
 
#21 ·
Drake quotes mechanic almost word for word. As for the p0430, it didn't set off any engine lights either, no trouble lights on at all. So I'll just have to wait and see what happens. I don't see how running a couple tanks of regular fuel could mess things up so badly... kinda makes me miss the days of the 85 Bronco II
 
#22 · (Edited)
Drake is right. The KS is almost useless in the Xterras. The KS on other vehicles will set of a CEL but Nissan did not cause it to set a CEL. Probably for a reason.

It is kind of useful in the supercharger as Pre-ignition/Detonation Can severely damage the internals of your Supercharged engine. Superchargers jack up combustion temperatures and pressure.


For this reason the Supercharger HAS to have Premium 91+. The octane rating doesn't indicate how much power the fuel delivers when burned. All grades of gasoline contain roughly the same amount of heat energy. Detonation occurs when part of the Air-Fuel mixture in your X ignites spontaneously due to the high compression. This is why Our Supercharged X'ers have to use 91. The 87 burns a lot more volatile then the 91. 87 burns very quickly and does not have great flame promigation. The 91 Burns a little slower and more controlled and helps to keep the temperature a little lower inside the combustion chamber.I have ran 87 Octane and 91 Octane in my Non-Supercharged Xterra and it did not do squat for driveability. The only thing it did was get me better gas mileage. But with that being said the price was alot higher so in the end I did not end up with more money.

IMHO when your engine starts Running like total shit you would know and stop it. So honestly the Knock sensor is obsolete. The knock sensor is there for people who do not know to immediately turn off their supercharged/turbo vehicles when it starts sounding like the engine is being beat by a hammer and shaking. People do not realize how delicate supercharged/Turbo charged engines are. They can be a hassle sometimes.


Honestly I would just get the codes you have fixed, the clutch replaced and forget about the Knock sensor code. It is worthless.

P0430
Your catalytic converter is not functioning properly.
An oxygen sensor is skewing its reading.
Your X has an exhaust leak.

These are the most likely causes.

Whoever told you that 87 and 91 are the same are full of shit. They specifically engineer all higher grades of gas to resist the burn process so that they do not pre-ignite. A low compression engine will not be badly affected by running higher octanes. An engine with very high compression cares a lot.
 
#23 ·
not sure about others but before i tore into my x to replace the ks, it read bad ks and high bank 1 when i read the code, i guess a faulty ks can also trigger other codes but after i replace mine, after the repair was done the code never came back. you maybe getting o2 codes because of your ks. imho
 
#24 ·
Drake is right. The KS is almost useless in the Xterras. The KS on other vehicles will set of a CEL but Nissan did not cause it to set a CEL. Probably for a reason.

It is kind of useful in the supercharger as Pre-ignition/Detonation Can severely damage the internals of your Supercharged engine. Superchargers jack up combustion temperatures and pressure.


For this reason the Supercharger HAS to have Premium 91+. The octane rating doesn't indicate how much power the fuel delivers when burned. All grades of gasoline contain roughly the same amount of heat energy. Detonation occurs when part of the Air-Fuel mixture in your X ignites spontaneously due to the high compression. This is why Our Supercharged X'ers have to use 91. The 87 burns a lot more volatile then the 91. 87 burns very quickly and does not have great flame promigation. The 91 Burns a little slower and more controlled and helps to keep the temperature a little lower inside the combustion chamber.I have ran 87 Octane and 91 Octane in my Non-Supercharged Xterra and it did not do squat for driveability. The only thing it did was get me better gas mileage. But with that being said the price was alot higher so in the end I did not end up with more money.

IMHO when your engine starts Running like total shit you would know and stop it. So honestly the Knock sensor is obsolete. The knock sensor is there for people who do not know to immediately turn off their supercharged/turbo vehicles when it starts sounding like the engine is being beat by a hammer and shaking. People do not realize how delicate supercharged/Turbo charged engines are. They can be a hassle sometimes.


Honestly I would just get the codes you have fixed, the clutch replaced and forget about the Knock sensor code. It is worthless.

P0430
Your catalytic converter is not functioning properly.
An oxygen sensor is skewing its reading.
Your X has an exhaust leak.

These are the most likely causes.

Whoever told you that 87 and 91 are the same are full of shit. They specifically engineer all higher grades of gas to resist the burn process so that they do not pre-ignite. A low compression engine will not be badly affected by running higher octanes. An engine with very high compression cares a lot.
Everyone can take this for what its worth, but these are my experiances in my S/C Xterra.


You're basically correct in your understanding of octane in fuel.

However its the necessity of using high octane fuel in the supercharged xterra where I disagree with you. The supercharged xterra - the VG33R engine - has a compression ratio of 8.3:1. 8.3:1!!! That is silly low compression. By comparision the 2003 Subaru wrx sti's compression ratio is 8.2:1 running 14.5 psi and the Mitsu Lancer Evo is 8.8:1 running 19.5. Yes, they have intercoolers but the Xterra supercharger is only producing ~6psi.


There is an SAE whitepaper out there on how to calculate heat and pressure rise in an ICE. Its actually fairly simple to setup the formula in an excel spreadsheet and have it graph the entire compression stroke. You can use this information to see how far away from pre-ignition this little 6psi s/c is on an 8.3:1 compression engine.

Now for my experiance I replaced my original VG33R engine with the VE33 (non R) engine with the 8.9:1 compression ratio, reinstalled the supercharger, bypassed the KS and use 87 octane fuel in the Chicago area. It's not exactly "long-term" testing yet but Have ~25,000miles on that setup with no issues. And this guy is in Canada. Way cooler climate than Chicago.
 
#25 ·
Thank u ShiftingSkys & Mac11 for your insight, I wasn't really clear on the differences with the SC, I know the basics of the internal combustion engine, but anything else I know is because it broke and I had to fix it. I've always driven beaters and done my own repairs, I've done clutches and trans swaps but not anything with a computer in it. I may not be as knowledgeable as many people but I'm quite capable once i've got my head around what i'm doing, and instructions are a must for me. I'm hoping to get my X back and not have do anything but reg maintainance for a good while, the mechanics know this and since I've got family financing the cost is less of an issue.
I was wondering though, if u put reg gas 87oct in and then add octane boost is that the same to the engine? Many people say it is, but they don't drive Xs.
Also, if the KS bypass is working and I'm not getting the code anymore should I leave it on or undo it? The mechanic said it doesn't matter, u guys seem to agree that the KS is redundant, but is it safe to run without one at all?
I hope I'm not annoying with all these questions, but when I find a source of info like u guys, especially with multiple view points, I like to soak up as much as I can :)
 
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